The present disclosure relates to information displays. More specifically, it relates to backlit optical information displays that include reflective polarizers.
Optical information displays are commonly used in televisions, laptop and desktop computers, hand-held devices such as mobile telephones, and other applications. A widely-used type of display is the liquid crystal (LC) display. A typical LC display is built around an LC panel, in which a liquid crystal with an associated electrode matrix is interleaved between a pair of absorptive polarizers. In an LC panel, portions of the liquid crystal have their optical state altered by an electric field applied via the electrode matrix. Depending on its state, a given portion (corresponding to a pixel or subpixel of the display) of the liquid crystal will rotate the polarization of light transmitted through it by a greater or lesser magnitude. Light progressing through entry polarizer, liquid crystal, and exit polarizer is attenuated to varying degrees depending on the optical state of the portion of liquid crystal that the light encounters. An LC display exploits this behavior to provide an electronically-controllable display having different appearances in different areas.
Because LC panels do not create light themselves, an LC display requires a source of illumination—typically either reflected ambient light, or more commonly, light from a backlight. The backlight generally includes an illumination device, which may include light sources such as light emitting diodes or fluorescent lamps, and a number of light management films between the illumination device and the LC panel. In general, the light management films may enhance the operation of a display by promoting more efficient and effective use of light.